Installation of underwater pollution control apparatus

ABSTRACT

A process for installing and forming an inverted drip pan over an underwater wellhead and its associated production manifold. One part of the pan is fixed above the production manifold, and another part of the pan is removably secured over the wellhead by use of means on the wellhead roof for coacting with a remotely operated running-in device for removably installing and retrieving such roof part.

United States Patent 1191 Childers 5] Nov. 6, 1973 [541 INSTALLATION or UNDERWATER 3,556,210 1/1971 Johnson 166/.5

POLLUTION CONTROL APPARATUS 3,653,215 4/1972 Crucet 3,662,823 5/l972 Murman et al. l66/.6 [75] Inventor: Thomas W. Childers, Woodland Hills, Calif. [73] Assignee: Esso Production Research Company, Primary Champion Assistant Examiner Richard E. Favreau Houston, Tex.

Attorney-Thomas B. McCulloch et al. [22] Filed: May 17, 1972 [2]] Appl. No.: 254,122

Related US. Application Data [57] ABSTRACT [63] Continuation-impart of Ser. No. 174, Jan. 2, i970,

Pat. No. 3,670,814. A process for installing and forming an inverted drip pan over an underwater wellhead and its associated [52] U.S. Cl 166/.5, 6l/l F production manifold. One part of the pan is fixed above [51] Int. Cl E2lb 43/01 the production manifold, and another part of the pan [58] Field of Search 166/5, .6; is removably secured over the wellhead by use of /1 F means on the wellhead roof for coacting with a remotely operated running-in device for removably in- [56] References Cited stalling and retrieving such roof part.

UNITED STATES PATENTS 3,454,083 7/1969 Brooks 166/5 6 Claims, 9 Drawing Figures PATENTEDMHY 5 I973 SHEET 10F 3 FIG.

PATENTED NOV 6 I975 SHEET 2 OF 3 PAIENTEUNBV GIHH SHEET 38F 3 CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending application Ser. No. 174, filed Jan. 2, 1970, now US. Pat. No. 3,670,814, patented June 20, 1972, and entitled Underwater Pollution Control.

FIELD OF THE INVENTION The present invention relates to methods of establishing oil confining structures over underwater well structures, and more particularly, to installing and forming an inverted drip pan over underwater well structures.

BACKGROUND OF THE INVENTION If oil produced from offshore strata escapes subsea well production facilities and rises to form oil slicks on surface waters, it may pollute not only those watersbut neighboring shorelines. Avoidance of this condition is imperative, yet leakage from submerged production equipment may not be detected until an oil slick appears on the surface of the sea. Minor butcontinuing leaks of production equipment may notproduce a noticeable surface slick, and large amounts of production may be lost as time passes.

In my copending application Ser. No. 174, referred to above, I have disclosed an inverted drip pan apparatus for the capture and confinement underwater of oil escaping into the sea from one or more submerged well structures and for the accumulation and local recovery, free of sea water, of oil which has escaped from one or more of submerged well structures. A

SUMMARY OF THE INVENTION This invention is a method of installing and forming an inverted drippan roof over both an underwater wellhead and a production manifold for such wellhead. According to the method, a manifold drip pan is arranged over a production manifold. A wellhead drip pan. is then rundown to the underwaterlocation in a tilted attitude for placement over the wellhead, the leading end of the tilted drip pan facing the direction of the production manifold. The tilted attitude reduces the projec tion of the wellhead drip pan such that the leading end of the wellhead drip. pan clears the nearedgeof the manifold drip pan facing the wellhead. The descent of the tilted wellhead drip pan is stopped below and behind the near edge of the manifold drip pan, and the wellhead drip pan is then pivoted about pivot means located behind and preferably below the near edge of the manifold drip pan. The pivoting movement is carried out soas to are the leading end of the wellhead drip pan upwardly, and to are the .trailing end of the wellhead drip pan downwardly, until the leading end of the wellhead drip pan is abutted under the near edge of the manifold drip pan, and the railing edge of the wellhead drip pan is positioned lower than the leading edge of the pan. This placement establishes an'inverted drip pan roof in which at least the wellhead drip pan portion slopes upwardly from a low point at the trailing end of the wellhead drip pan. It thereby establishes a continuous, and at least over the wellhead, upwardly inclining, passageway over the wellhead and the production manifold along which fugitive oil fluids from the wellhead or the production manifold, or both, will be directed by gravity flow to an uppermost portion of the manifold cover for confinement.

The invention will be more fully understood by a detailed description of it in connection with the drawings which are now described.

DESCRIPTION OF THE DRAWINGS FIG. 1 constitutes a combined longitudinal section and side elevational view of an underwater pollution control apparatus installed above a submerged well structure;

FIG. .2 illustrates the installation of a portion of the underwater pollution control apparatus, shown in longitudinal section; I

FIG. 3 is a rear elevational view taken along the lines 3-3 of FIG. 2;

FIG. 4 is an enlarged longitudinal section of the running-in toll illustrated in FIG. 2;

FIG. 5 is a top elevational view takenalong the lines 5-5 of FIG. 4;

FIG. 6 is a longitudinal sectional and side elevational view depicting the installation of a portion of the underwater pollution control apparatus for opposed submerged well structures;

FIGS. 7(a)-(c) illustrate another method ofinstalling a portion of the pollution control apparatus;

FIG. 8 is a cross sectional view taken along the lines 8-8 of FIG. 7(a); and

FIG. 9 is an enlarged side elevational viewv of a portion of the pollution control apparatus illustrated in FIGS. 7(a)(c).

- DESCRIPTION OF THE PREFERRED EMBODIMENTS An underwater pollution control device A is illustrated in FIG. 1 which as viewed is already installed over a submerged well structure B. The submerged well structure B includes a wellhead 10, which surmounts a well 11 illustrated as a dual completion well; production lines 12, 13, which produce dual completion well 11; and production manifolds 14,15, into which production from production lines 12, 13 feeds by way of draulic lines (eig. lines 22, 23) to an electrohydraulic of a template structure 27, which includes a base 28 mounting front and rear guideposts 29a and 2%, respectively, from which guide wires 30 are extended to a fixed or floatingplatform on the ocean's surface.

The underwater pollution control device A includes a roof 31 extending over the well structure B. Referring particularly to FIG. 1, roof 31 takes the form of an inverted pan, with a top surface 32 and side curtains 33,

and includes a portion 34 over the manifold and a portion 35 over the wellhead. The manifold cover pan 34 is affixed over production manifolds 14, 15, suitably by structural members 36 secured to the header portion 37 of the uppermost manifold 14. Wellhead cover pan 35 is removably secured above wellhead by structure hereinafter described coacting with the guideposts 29a and 29b of the template 27, in order that the wellhead cover pan 35 may be removed for vertical reentry to perform workover operations and the like.

In the embodiment illustrated in FIG. 1, roof 31 has a sloped configuration over wellhead structure B, the roof ascending from the portion 35 covering the wellhead to the portion 34 covering the manifold. The forward portion 38 of the wellhead cover pan 35 is inserted under the rear portion 39 of the manifold cover pan 34 to form a continuous and upwardly inclining passage from wellhead cover pan 35 to manifold cover pan 34 by which oil fluids, of lighter specific gravity than water, and fugitive from well structure B, are directed to flow by gravity upward under manifold cover pan 34. Manifold cover pan 34 includes as oil fluid collecting structure a transverse passage 40 provided by a gutter 41 formed in the forward portion of manifold cover pan 34. Gutter 41 converges from side curtains 33 of manifold cover pan 34 to drain into a standpipe 42 which empties into a roof receiving chamber 43. For a multi-wellhead template, one manifold cover pan 34 may receive oil percolating upward from a plurality of wellhead cover pans 35 in which centrally peaked gutter 41 delivers tributary oil from any roof portion 34 or 35 to the central roof receiving chamber 43.

Instead of being inclined upwardly in the same direction as wellhead cover pan 35 so as to direct fugitive oil fluids to a collecting structure 40 at an uppermost end remote from the near portion 39 of the manifold cover pan, the manifold cover pan may be horizontally oriented or may be inclined downwardly from the near portion 39 near the forward end 38 to the wellhead cover pan. lf inclined downwardly, the transverse passage 40 would be situated at near portion 39 in an uppermost location in the roof 31. The forward or leading end 38 of the wellhead cover pan would continue to be placed underthe near edge 39 of the manifold cover pan, such that fugitive oil passing upwardly under wellhead cover pan 35 would empty into the transverse collecting structure 40.

Oil confined under roof 31 above oil-water interface 44 is removed from its underwater confinement and discharged into well structure B free of sea water by means of a fluid conduit 45 connecting roof 31 and well structure 8. Referring to FIG. 1, fluid conduit 45 has an inlet 46 opening into the receiving chamber 43 of roof 31 and an outlet 47 opening into a production line of well structure B, suitably downhole production tubing, wellhead production lines 12, 13 or, as illustrated, into header portion 37 of production manifold 14. Admission into inlet 46 of oil above interface 44 is controlled by a normally closed inlet valve 48 operatively associated with an oil-water interface level detecting device 49 which opens inlet valve 48 when the oilwater interface 44 reaches a predetermined minimum level below inlet 46 and closes inlet valve 48 when interface 44 climbs to a selected higher level below inlet 47 with drainage of oil into fluid conduit 45. Suitably, interface level detecting device 49 may include a relay for electrically actuating valve 48 on closure of the relay by downward movement of float 50 on pivot arm 51 to the predetermined minimum location within side curtains 33 of roof 31 below inlet 46. (Other oil-water interface level detecting devices suitably include solid state electrical micro switches, capacitance probe-type oil detectors, magnetic permeability switches and the like, as known to the art, although the float actuated mechanical link is preferred for its long service life and reliability.) When inlet 46 is opened, oil above interface 44 is driven into fluid conduit 45 by the heavier sea water if line pressure in production manifold 14 is less than the hydrostatic pressure of the water at the level of the underwater structure. If line pressure is greater than the hydrostatic pressure at that level, oil from the production mainfold may backflow through fluid conduit 45, driving interface level 44 down within receiving chamber 43 to a predetermined maximum level to which interface level detecting device 49 responds, as by closure of a second stage relay, and engages circuitry leading to production control unit 24 to shut in production from well structure B. Response of interface level detecting device 49 to attainment of the predetermined maximum level may also engage circuitry which may be provided for electrical connection to an indicator installed at a remote accessible location to signify accumulation under roof 31 of a predetermined maximum volume of oil above the predetermined maximum level. Alternatively, as illustrated in FIG. 1, a capacitance probe 52 or other level detecting means may be separately installed in the lower portion of the receiving chamber 43, instead of being integrated with the structure of the device 49 detecting the predetermined minimum level, for connection to electrical circuitry leading to a remote indicator and/or operative connection to production control unit 24. A check valve 53 may suitably be provided in fluid conduit 45 to prevent backflow into chamber 43 of oil from production manifold 14. If so, when inlet 46 is opened on attainment of the predetermined minimum volume and forward flow through fluid conduit 45 is prevented by a higher pressure in the production line, well structure B will be shut in by continued collection of fugitive oil by roof 31 if the predetermined maximum volume interface level is attained.

As hereinbefore stated, manifold cover pan 34 is affixed over production manifolds 14, 15. Suitably, manifold cover pan 34 may be attached to its mount prior to lowering of the well structure B on template 27 into place on ocean bottom 26.

Removable wellhead cover pan 35 is installed after well structure B and manifold cover pan 34 are set in place on ocean bottom 26. In FIGS. 2-6, the operation of structure of wellhead cover pan 35 coacting with a remotely operated running and retrieving tool for removably securing wellhead cover pan 35 above wellhead 10 is illustrated for the embodiment of wellhead cover pan 35 depicted in FIG. 1. Referring particularly to FIGS. 2 and 3, wellhead cover pan 35 is pivotally hinged in its forward portion by means of a plurality of hinge pins seated in mounting rings 76 affixed to confronting sides of guide sleeves 77. The top surface 32 of wellhead cover pan 35 mounts a crossbar 78 between upstanding ears secured to the rear of the center of wellhead cover pan 35. A semicircular stop is braced behind ears 79 at an acute angle with top surface 32 by a brace 81.

Coacting with the structure of wellhead cover pan 35 is a running and retrieving tool indicated generally by reference numeral 82. Referring to FIG. 2, tool 82 includes a central tubular body or mandrel 83 connected to a tubular running-in string 84, as by threaded attachment of an upward box in mandrel 83 with a lower pin end of the running-in string 84. Referring to FIG. 3, the lower end of tubular mandrel 83 is constituted as a tubular neck 84 terminating in a piston head 85, which attaches a plurality of dependent, normally extended, opposed spring fingers 86. A latching sleeve 87 surrounds piston head 85 in a larger inner diameter lower portion of the sleeve and surrounds lower neck 84 of tubular body 83 in a smaller inner diameter upper portion, which includes in its inner circumference a circular recess 88 housing a suitable seal ring or gasket 89, such as an 0-ring. A circumferential recess 90 is provided in the outer circumference of piston head 85 to house a suitable seal ring or gasket 91. Sealing members 89 and 91 together prevent leakage of fluid between tubular body 83 and latching sleeve 87. Spring fingers 86 are provided with outside stops 92 which limit downward extension of latching sleeve 87 on neck 84 and piston head 85 of tubular body 83. Force giving rise to a downward extension of latching sleeve 87 is imparted to sleeve 87 by a helical spring encompassing neck 84 and compressed between outer shoulders 94 and 95, respectively, of tubular body 83 and latching sleeve 87. In full extension on neck 84 and piston head 85, latching sleeve 87 defines an annular space 96 between its inner shoulders 97 and the upper inner shoulders 98 of piston head 85. In operation, hydraulic fluid is pumped through tubular passageway 99 into annular space 97 to retract latching sleeve 87 on the circumference of poston head 85 against the compressive force of spring 93, thereby opening spring fingers 86 for closure about crossbar 78 on wellhead cover pan 35. Bydraulic fluid is then withdrawn from annular space 97 in balanced measure against the force of spring 93 so that latching sleeve 87 descends about piston head 85 until the downward extension of its movement is limited by stops 92, thereby closing and locking spring fingers 86 inwardly about crossbar. 78 of wellhead cover pan 35. As illustrated in FIG. 2, running-in string 84, when hoisted, permits the wellhead cover pan to rotate on pins 75 mounted to guide sleeves 77 to-produce a tilted attitude which reduces the projected area of the leading edge 38 of wellhead cover pan 35 upwardly until leading edge 38 is abutted under the rear edge 39 of manifold cover pan 34, and at the same time arcs downwardly the trailing end of wellhead cover pan 35 until it is deposited on cross number 101. Tool 82 is then released from crossbar 78 of wellhead cover pan 35 by pumping hydraulic fluid into annular space 96 to retract latching sleeve 87, permitting spring fingers 86 to expand outwardly to release the crossbar. Runningin string 84 is then retrieved to the surface. As reference to FIG. 6 illustrates, wellhead cover pans 35 may be so installed in back-to-back multi-wellhead template Alternative structures of wellhead cover pan 35 for coaction with running and retrieving tool 82 for removably securing wellhead cover pan 35 above wellhead 10 in the embodiment of wellhead cover pan 35 depicted in FIG. 1 is illustrated in FIGS. 7(a)-7(c) taken with FIGS. 8 and 9. In this form, wellhead cover pan 35 is run in without the necessity of using a conventional guidepost system. As in the embodiment discussed in connection with FIGS. 2-6, wellhead cover pan 35 is wellhead cover pan such that when the wellhead cover 7 pan is run in by string 84 guided by guide sleeves 77 running on guide wires 30 from guidepost 29a, the leading edge 38 of the wellhead cover pan 35 clears the rear edge 39 of fixed manifold cover pan 34. During descent, the tilted attitude of the wellhead cover pan is maintained by abutment of semicircular stop 80 against latching sleeves 87 of tool 82, as depicted by FIGS. 2, 4 and 5. Descent of wellhead cover pan 35 is stopped when guide sleeve 77 impinges upon limit ring 100 attached to guidepost 29a. As shown in FIG; 2, the leading edge of the wellhead cover pan is then below and behind the rear edge 39 of manifold cover pan 34. Further downward movement of running-in string 84 pivots or rotates wellhead cover pan 35 about the pivot axis of hinge pins 75, semicircular stop 80 disengaging latching sleeve 87, until wellhead cover pan'35 is deposited on a cross member 101 spanning rear guidepost 29b. As shown in FIG. 2, this pivotal movement of wellhead cov'er pan 35 on hinge pins 75 serves to arc the provided with an off-center crossbar 78 secured to top surface 32 by a pair of ears 79. Attachment of the running tool to off-center crossbar 78 as shown in FIG. 7(a) causes the forward edge 38 of the cover 35 to rotate down to a tilted attitude reducing the projected area of cover 35 so that, when lowered, it clears the rear edge 39 of the fixed manifold cover pan 34. Referring to FIG. 8 taken with FIG. 7(a), the undersurface of top 32 of wellhead cover pan 35 is provided with a pair of notched ribs 102 longitudinal and inboard of lateral side curtains 33. Each of the ribs 102 is tapered to define a notch 103 between a leading anterior portion 104 and a trailing posterior portion 105. As the wellhead cover pan 35 is lowered, the leading portion 104 contacts a cross member 106 provided in structure erected on template 27 (FIG. 7(a)). Leading portion 104 then slides forward on its edge until it is stopped by notch 103. As lowering continues, wellhead cover pan 35 rotates "about notch 103 so that the forward edge 38 of the cover 35 is under the fixed manifold cover pan 34, as depicted in FIG. 7(c). In this position, the rear end of top surface 32 rests on a cross support member of framework on template 27. As depicted in FIG. 9, notch 103 may include a'recess within rib 102 forhooking rib 102 on cross member 106 to prevent slippage. Wellhead cover pan 35 may run in using an external guidance system other than the conventional guidepost system.

Having fully and particularly described this invention, and having disclosed the best modes contemplated for the purposes of this invention, I claim and desire to secure by-Letters Patent:

1. A method of forming an inverted drip pan roof over an underwater wellhead and a production manifold for such wellhead, comprising:

arranging a manifold drip pan over said production manifold,

running a wellhead drip pan down in a tilted attitude I for placement over said wellhead, the leading end of said tilted pan facing in the direction of said production manifold, said tilted attitude providing a reduced projection of said wellhead drip pan such that said leading edge of the wellhead drip pan clears a near edge of the manifold drip pan facing said wellhead, means on such wellhead drip pan coacting with means on a running and retrieving tool to releasably lock said wellhead drip pan to said tool, stopping the descent of said tilted wellhead drip pan such that said leading end thereof is below and behind said near edge of said manifold drip pan,

pivoting said wellhead drip pan about pivot means behind said manifold drip pan such that said leading end of the wellhead drip pan arcs upwardly until the leading end is abutted under said near edge of the manifold drip pan and such that the trailing end of the wellhead cover pan arcs downwardly until stopped at a location lower than said leading edge so that the wellhead cover pan slopes upwardly from trailing end to leading end, thereby forming a continuous upwardly inclining passage from wellhead cover pan to manifold cover pan, along which fugitive oil fluids are directed by gravity flow to the manifold cover pan.

2. The method of claim 1 wherein means on said wellhead drip pan coact with said running and retrieving tool to define the tilt angle of the wellhead cover pan during its descent.

3. The method of claim 1 wherein said wellhead drip pan has notched longitudinal rib means on its underside spaced inwardly from the sides of such drip pan, and wherein the descent of the wellhead co'ver pan is stopped by impingement of the notch of said rib means on pivot means located below and behind said near edge of said manifold drip pan.

4. The method of claim 1 further comprising: guiding the descent of the wellhead drip pan with guide lines passingthrough guide sleeves connected to such cover pan and attaching to guideposts spaced between said wellhead and said production manifold.

5. The method of claim 4 wherein the descent of said wellhead drip pan is stopped by limit means located on said guideposts.

6. The method of claim 4 wherein said guide sleeves are connected to pivot pins extending laterally from said wellhead drip pan at a location between said leading end of the wellhead drip pan and the transverse midline of said wellhead drip pan. 

1. A method of forming an inverted drip pan roof over an underwater wellhead and a production manifold for such wellhead, comprising: arranging a manifold drip pan over said production manifold, running a wellhead drip pan down in a tilted attitude for placement over said wellhead, the leading end of said tilted pan facing in the direction of said production manifold, said tilted attitude providing a reduced projection of said wellhead drip pan such that said leading edge of the wellhead drip pan clears a near edge of the manifold drip pan facing said wellhead, means on such wellhead drip pan coacting with means on a running and retrieving tool to releasably lock said wellhead drip pan to said tool, stopping the descent of said tilted wellhead drip pan such that said leading end thereof is below and behind said near edge of said manifold drip pan, pivoting said wellhead drip pan about pivot means behind said manifold drip pan such that said leading end of the wellhead drip pan arcs upwardly until the leading end is abutted under said near edge of the manifold drip pan and such that the trailing end of the wellhead cover pan arcs downwardly until stopped at a location lower than said leading edge so that the wellhead cover pan slopes upwardly from trailing end to leading end, thereby forming a continuous upwardly inclining passage from wellhead cover pan to manifold cover pan, along which fugitive oil fluids are directed by gravity flow to the manifold cover pan.
 2. The method of claim 1 wherein means on said wellhead drip pan coact with said running and retrieving tool to define the tilt angle of the wellhead cover pan during its descent.
 3. The method of claim 1 wherein said wellhead drip pan has notched longitudinal rib means on its underside spaced inwardly from the sides of such drip pan, and wherein the descent of the wellhead cover pan is stopped by impingement of the notch of said rib means on pivot means located below and behind said near edge of said manifold drip pan.
 4. The method of claim 1 further comprising: guiding the descent of the wellhead drip pan with guide lines passing through guide sleeves connected to such cover pan and attaching to guideposts spaced between said wellhead and said production manifold.
 5. The method of claim 4 wherein the descent of said wellhead drip pan is stopped by limit means located on said guideposts.
 6. The method of claim 4 wherein said guide sleeves are connected to pivot pins extending laterally from said wellhead drip pan at a location between said leading end of the wellhead drip pan and the transverse midline of said wellhead drip pan. 